2026 Polling Index · Midterm poll error
How far off were the final midterm polls?
Each bar is one race’s polling average over the last three weeks, minus the certified result, in two-party margin. Bars to the right mean the polls were too Democratic; bars to the left, too Republican.
Window: polls ending 0–21 days before Election Day in the 2018 and 2022 midterms
Final polling error by race
Both midterms finished close on average, but individual races still missed by 5 to 14 points. The column beside each state is its margin in the previous presidential race. Faded bars rest on one or two polls. Tap or hover a bar for the matchup.
2018
2022
The redder the state, the more the polls favored Democrats
Each dot is a race, placed by the state’s previous presidential margin and its final polling error. In both midterms, polls overstated Democrats in Trump states and overstated Republicans in Democratic states.
Senate and governor polls missed the same way
Governor polls landed about as close on average and showed the same red-state, blue-state split, slightly weaker than in the Senate races.
How this is measured
Polls come from the FiveThirtyEight Senate polls archive, general-election matchups between the two eventual principal candidates only. Margins are two-party: undecideds are dropped from each poll and third-party votes from each result. A race’s final error is the simple mean of its polls ending within 21 days of Election Day, so a pollster that released several polls counts several times.
The race average counts every race once. The poll average weights by poll count, which tilts it toward the heavily polled battlegrounds. In 2022 those two disagree in sign: the battlegrounds missed slightly toward Republicans while thinly polled safe seats missed toward Democrats.
Governor polls come from the Silver Bulletin raw-polls file, which keeps polls of each race’s final matchup that ended within 21 days of Election Day, scored on the same two-party metric. It draws on a slightly different poll set: on Senate races it lands within a point of the FiveThirtyEight archive in each cycle. Governor races with no poll in the window are left off.
Independents who ran as the de facto candidate of one side are scored on that side: King and Sanders (D, 2018) and McMullin (D, Utah 2022). Results are certified returns from the MIT Election Data & Science Lab. Presidential margins are two-party: 2016 for the 2018 races and 2020 for the 2022 races.